An occlusion or obstruction in an elongated body cavity such as in a vessel especially in an artery, is generally initially widened in that deposits such as plaque are removed, for example, by cutting out and suctioning or the like. However, this cannot take place up to the tissue material of the vessel because, at this point, there is a risk of injury.
If there is only a narrowing, for example, a stenosis, but not a complete occlusion, such as, for example, with an enlarged prostrate in the vicinity of the urethra, or after a certain through-flow area has been created in the previously complete occlusion, a radial widening of the stenosis is desired. Therefore, this is carried out not only in blood vessels, but also in other body passages or tubes such as the ureter, urethra, bile ducts, etc.
Previously, this function has been fulfilled by a balloon catheter, optionally with a double internal diameter, which brings about an instantaneous radial widening. This widening of the stenosis should remain permanently after the removal of the balloon catheter, but this is generally not the case. Therefore, permanent widening of a stenosis has already been proposed. Thus, a widening part is mounted on a balloon catheter in an axially fixed manner, with the widening part being introduced with the catheter and, by widening action, the catheter is plastically deformed in such a manner that the radial dimensions of the widening part increase and the widening part is pressed into the stenosis wall and, after releasing the air from the catheter, the catheter can be removed again, whereas, the widening part, in the plastically deformed state, remains in its location. For this purpose, a proposal has already been made for a sleeve in the form of an "optionally perforated" plastic or tissue-compatible metal envelope.
A significant disadvantage of the above proposed process resides in the fact that the sleeve must be introduced into the stenosis resting on the outer circumference of a catheter. First, the axial fixing is complicated and can either not be reliably achieved, so that the part can be left behind on advancing the catheter or a separate release of the part from the catheter causes problems. In addition, a widening part located externally on the catheter can lead to tissue damage. Finally, the widening through the balloon catheter in the case of such a part must initially lead to a radial extension, which is well beyond that which is ultimately desired for the widening part, because such parts, such as conventional compatible materials, to the extent that they have an adequate strength to maintain the stenosis open, have a considerable elastic deformation range, before there is a permanent plastic deformation to the desired radius. This more particularly occurs if the stenosis or the surrounding tissue material is pressed radially from the outside against the widening part.